Compensating valve for fluid pressure systems



Jan. 4, 1949.

E. H. JOHNSON COMPENSATING VALVE FOR FLUID PRESSURE SSTEMS Filed Aug. 12, 1943 ttorneys Patented Jan. 4, 1949 COMPENSATING VALVE FOR FLUID PRESSURE SYSTEMS Edward Harry Johnson, Coventry, England, as-

signor to The Keelavite Company Limited, Allesley, Coventry, England, a company of Great Britain Application August 12, 1943, Serial No. 498,374 In Great Britain November 30, 1942 11 Claims.

1 This invention relates to rotary engines, pumps and the like of the kind forming the subject of United States of America patent application Serial No. 456,060 whether intended primarily to act upon or be acted upon by fluid or incorporated in fluid pressure apparatus such as hydraulic' transmission apparatus and, as in the specification accompanying the above patent application such rotary engines, pumps and the like will for the sake of convenience be referred to as rotary engines.

In rotary engines of the kind referred to the blade chamber, the rotor and the abutment are contained within a casing with means for maintaining within this casing durin operation of the rotary engine, a fluid pressure between the inlet and outlet pressures, that is to say between the pressures respectively in the parts of the blade chamber in communication with the inlet and outlet ports at any moment, The present invention is concerned with arrangements in which such fluid pressure is maintained by a relief valve so acted upon differentially respectively by the pressure in the casing on the one hand and the inlet and outlet pressures on the other hand that it permits escape of fluid from a relief port in the casing to the inlet or outlet passage, whichever is at lower pressure or to atmosphere or elsewhere if and when the pressure in the casing exceeds the appropriate value and automatically closes the relief port again when the correct pressure has been re-established.

When such arrangement is applied to a rotary engine in which, in order to enable the capacity of the rotary engine to be varied, one end wall of the blade chamber is movable axially with the blades relatively to the other end wall through which the blades extend and slide, it has been proposed in the specification of the prior patent application referred to above to provide a compensating piston moving with the axially movable end wall and disposed in a cylinder communicating with the interior of the casing, the area of the piston correspondingapproximately to the efiective area of the axially sliding parts so that movement of the compensating piston in efiect withdraws from or displaces into the casing the fluid which would otherwise be respectively forced from orsucked into the casing by the sliding parts of the rotary engine.

The object of the present invention is to provide an arrangement in which the quantity of fluid within the casing will be automatically adjusted as and when the axially moving parts of the rotary engine are moved to vary its capacity,

1 without the necessity for a compensatin piston.

To this end according to the present invention valve apparatus is provided which not only permits fluid to escape from the casing through a relief port as and when the pressure in the casing exceeds the appropriate value but also permits fluid to enter the casing from the high pressure side of the rotary-engine as and when the pressure in the casing falls below the appropriate value.

Thus when the axially movable parts of the rotary engine are moved in one direction and thus reduce the efiective capacity of the casing, the pressure rise in the casing produced as the axial movement'is effected causes the valve apparatus to open the relief port to permit the appropriate escape of fluid from the casing and similarly, when the axially movable parts of the rotary engine are moved in the other direction the decrease in pressure in the casing causes the valve apparatus to operate to permit fluid to enter the casing under pressure so as to maintain the desired pressure and permit the required axial movement to take place readily.

The invention is particularly but not exclusively applicable to arrangementsof the kind referred to wherein the relief valve is in-the form of a' two diameter piston the largest diameter of which is acted upon by the pressure in the easing, and one construction according to the invention employing such a valve is illustrated somewhat diagrammatically in the accompanying drawings, in which Figure 1 is a diagrammatic View showing the various fluid connections, and

Figure 2 is a sectional side elevation of the valve.

In the construction illustrated the valve comprises a valve housing A in Which is formed a valve cylinder or bore having a larger diameter part B and a smaller diameter part B Mounted to slide freely in this bore is a piston valve having a larger diameter part C and a smaller diameter part C lying respectively in the larger and smaller diameter parts of the bore.

Communicating with the right-hand end of the larger diameter part B of the bore is a passage D leading from the interior of the casing of the rotary engine indicated at D and also communicating with a passage D leading to a port D in the wall of the smaller diameter part B of the bore.

Communicating with a port E at an intermediate point in the length of the larger diameter part B of the bore and with a port E opening into the annular space F between the larger diameter part of the piston and the left-hand end of the part B of the bore is a passage E leading either to the low pressure port of the rotary engine or to a tank or reservoir at low pressure.

The left-hand end of the smaller diameter part B of the bore communicates with the high pressure port of the rotary engine through a passage G and if desired a changeover valve B enabling the passage G to be connected to the inlet or outlet port of the rotary engine respectively through passages G G3 according to the direction of rotation of the engine and/or whether it is acting as a pump or a motor and therefore which port contains fluid at the higher pressure.

The smaller diameter part C of the piston valve has a surface area approximately half that of the larger diameter part C. It will therefore be seen that during normal operation of the rotary engine the valve will maintain a pressure within the casing equal to approximately half that at the high pressure port of the rotary engine since as and when the pressure in the casing tends to rise above this the piston valve will move to the left and open the port E to permit escape of fluid from the casing until the pressure therein has again dropped to half that at the high pressure port. Further when the axially movable parts of the rotary engine are moved in the direction which reduces the effective capacity of the casing, the pressure rise in the casing produced by the axial movement will cause the piston valve similarly to move to the left to permit escape of fluid from the casing while when the axially movable parts of the rotary engine are moved in the other direction and thus increase the effective capacity of the casing, the pressure drop in the casing thus produced will cause the piston valve to move to the right so that the port D will be uncovered to permit high pressure fluid to flow from the passage G, through the port D to the interior of the casing to restore the pressure and permit the desired axial movement to take place readily.

In the construction illustrated in Figure 2 the change-over valve G is arranged to connect the passage G to the high pressure port of the rotary engine automatically whichever this may be and to this end is in the form of a ball valve lying in a chamber G communicating at all times with the passage G and having seatings G G at its opposite ends through which it communicates respectively with the passages G G It will thus be seen that when the passage G communicates with the high pressure port the valve will be maintained by the higher pressure in contact with the seating G so that the passage G only communicates with the passage G whereas when the passage G communicates with the high pressure port of the engine this pressure will maintain the valve in engagement with the seating G so that only the passage G communicates with the passage G.

In a modified arrangement instead of an automatic valve such as that shown in Figure 2 a manually operated change-over valve may be provided. Further where the passage E leads to the low pressure port it may communicate with both ports through a change-over valve so that it can be connected to the appropriate port according to the direction of rotation of the rotary engine and/or whether it is being used as a pump or amotor.

What I claim as my invention and desire to secure by Letters Patent is:

1. Valve apparatus for maintaining and controlling pressure in a closed chamber of a fluid pressure system subject to fluctuations in pressure and functioning to maintain the pressure in the chamber at a level between the pressures on the high and low pressure sides of said fluid pressure system, said valve apparatus comprising a valve housing having at least one continuously open port communicating with said chamber, at least one relief port communicating with a relief passage and at least one pressure port communicating with the high pressure side of the system, and a valve member arranged in the housing for operation by the pressure in said chamber, and so controlling the ports that when the pressure in the chamber drops below an appropriate value the valve brings into communication the pressure port with said open port, and when the pressure in said chamber rises above the appropriate value the valve brings into communication the relief port with said open port.

2. Valve apparatus for maintaining the pressure in an intermediate chamber of a fluid pressure system subject to variations in pressure between the pressures of the inlet and outlet sides of said chamber comprising a two diameter cylindrical valve housing and a two diameter piston valve slidably mounted in the housing, said housing having two ports communicating with the interior of said chamber and opening respectively through the larger diameter end of the valve housing and through the circumferential wall of the smaller diameter part of the housing, and ports communicating with the low pressure side of said chamber and opening through the circumferential wall of the larger diameter part of the housing at points respectively within the sliding range of the valve and between the larger diameter part of said valve and the smaller diameter part of the housing, and a port opening into the smaller diameter end of the housing and communicating with the high pressure side of said chamber, said valve being arranged to move under the influence of pressures applied through said ports so that when the pressure within the chamber rises above an appropriate value the port in the larger diameter end of the housing is brought into communication with the port opening through the circumferential wall of the larger diameter part of the housing, and when the pressure within the chamber drops below an appropriate value the port opening into the smaller diameter end of the housing is brought into communication with the port opening through the circumferential wall of the smaller diameter part of the housing, and the ports opening through the circumferential walls of the two parts of the housing at other times being closed by the valve.

3. The combination with a fluid pressure system comprising a closed chamber into which open the working clearances of relatively movable parts of the system between which said chamber is disposed, of a two diameter cylindrical valve housing, a two diameter piston valve slidable in said housing, the largest end surface of the valve being subject to the pressure within the chamber and the other two end faces of the valve being subject respectively to the pressures of the inlet and outlet sides of the chamber, said housing having ports disposed in its circumferential walls in such positions as to be controlled by the valve to bring the interior of the chamber into communication with the high pressure side aezsassc of the system when the valve is moved in one direction by the pressure within the chamber being lower than the appropriate value and to bring the interior of the chamber into communication with the low pressure side of the system when the valve is moved in theopposite direction by the pressure in the chamber being higher than the appropriate value.

4. Valve apparatus according to claim 3 having means for selectively placing that face of the piston valve that is to be subjected to the pressure of the high pressure side of the chamber in communication with either the outlet or inlet side of the system.

5. Valve apparatus according to claim 2 in combination with change over valve means for placing the port that opens through the smaller diameter end of the valve housing in communication with either the high or low pressure side of the chamber.

6. Valve apparatus in accordance with claim 3 in combination with change over valve means comprising an auxiliary valve housing provided with three ports communicating respectively with the main valve housing and the high and low pressure sides of the chamber, and a valve member disposed within the auxiliary housing and arranged to be moved by pressure diflerences between the two sides of the system for closing the port that leads to the side of the lower pressure and bringing the port leading to the side of higher pressure into communication with the main valve housing.

7. Valve apparatus in accordance with claim 2 in combination with change over valve means comprising an auxiliary valve housing provided with three ports communicating respectively with the main valve housing and the high and low pressure sides of the chamber, and a valve disposed within said auxiliary housing and arranged to be moved automatically by pressure differences between the two sides of the chamber to close the port leading to the low pressure side of the chamber and brings the port leading to the high pressure side of the chamber into communication with the main valve housing.

8. Valve means in accordance with claim 3 in combination with change over valve means comprising an auxiliary valve housing provided with three ports communicating respectively with the main valve housing and the high and low pressure sides of the chamber, and a ball valve freely movable in the auxiliary housing for movement by pressure difierences between the two sides of the system for closing the port leading to the low 2 pressure side of the chamber and bringing the port leading to the high pressure side of the chamber into communication with the main valve housing.

9. Valve apparatus for regulating the pressure in a chamber subject to fluctuations in pressure comprising a valve housing having two communicating chambers of unequal diameter, a valve freely movable axially in said housing chambers, said valve having its ends of unequal areas and each end partly filling the space in one of said valve chambers, a port in the end of the larger of said valve chambers communicating with said fluctuating pressure chamber, a port in the side wall of the smaller of said valve chambers communicating with said fluctuating pressure chamber, and adapted to be over-travelled by the small end of said valve, exhaust ports in the side wall of said larger valve chamber spaced apart a distance greater than the length of the end of said valve of'larger area and adapted to be over,- travelled thereby at opposite ends of its movement, and a port in the endof said smaller valve chamber communicating with a source of fluctuating high pressure through a branch controlled by a check valve, thereby said valve will respond to an increase in pressure in said fluctuating pressure chamber with respect to said source of high pressure to open one of said exhaust ports and will respond to a decrease in pressure in said fluctuating pressure chamber with respect to said source of high pressure to open communication therewith through said smaller valve chamber from said source of high pressure and said fluctuating pressure chamber is maintained at a mean of the fluctuating diflerence in pressure.

10. Valve apparatus for regulating the pressure in a chamber subject to fluctuations in pressure comprising a valve housing having two communicating chambers of unequal diameter, a valve freely movable axially in said housing chambers, said valve having its ends of unequal areas and each end partly filling the space in one of said valve chambers, a port in the end of the larger of said valve chambers communicating with said fluctuating pressure chamber, a port in the side Wall of the smaller of said valve chambers communicating with said fluctuating pres sure chamber, and adapted to be over-travelled by the small end of said valve, an exhaust port in the side wall of said larger valve chamber adapted to be covered by said valve at one end of its movement, and a port in the end of said smaller valve chamber communicating with a source of fluctuating high pressure, whereby said valve will respond to an increase in pressure in said fluctuating pressure chamber with respect to said source of high pressure to open one of said exhaust ports and will respond to a decrease in pressure in said fluctuating pressure chamber with respect to said source of high pressure to open communication therewith through said smaller valve chamber from said source of high pressure and said fluctuating pressure chamber is maintained at a mean of the fluctuating difference in pressure.

11. Valve apparatus for regulating the pressure in a chamber subject to fluctuations in pressure comprising a valve housing having two communicating chambers of unequal diameter, a valve freely movable axially in said housing chambers, said valve having its ends of unequal areas and each end partly filling the space in one of said valve chambers, a port in the end of the larger of said valve chambers communicating with said fluctuating pressure chamber, a port in the side wall of the smaller of said valve chambers communicating with said fluctuating pressure chamber, and adapted to be over-travelled by the small end of said valve, an exhaust port in the side wall of said larger valve chamber adapted to be covered by said valve at one end of its movement, and a port in the end of said smaller valve chamber communicating with a source of fluctuating high pressure through a passage having two branches, and a reversible valve in said passage controlling the flow of fluid therethrough, whereby said valve will respond to an increase in pressure in said fluctuating pressure chamber with respect to said source of high pressure to open one of said exhaust ports and will respond to a decrease in pressure in said fluctuating pressure chamber with respect to said source of high pressure to open communication therewith through said smaller valve chamber from said source of h s pres ur and. sa fluctuatin press re 1 1 1 her is ma nt n d. at a me n of the f uctuatin difierence in pressure,

EDWARD HARRY JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Witteman Aug 23, 1927 Nu be 

